Liquid crystal / in situ ring-opening polymer electrolyte, lithium ion battery and preparation method thereof

Abstract

The present application relates to a kind of liquid crystal / in situ ring-opening polymer electrolyte, lithium ion battery and its preparation method. First, liquid crystal monomer, cyclic ether and lithium salt are mixed to form a mixture;Then the mixture is subjected to polymerization reaction, and liquid crystal / in situ ring-opening polymer electrolyte is obtained.Compared with prior art, the liquid crystal / in situ ring-opening polymer electrolyte of the present application uses in situ ring-opening polymer as the main matrix, and liquid crystal as organic solid filling material, so that the room temperature conductivity of the polymer electrolyte reaches 1*10 ‑4 S cm ‑1 Above, finally applied in lithium ion battery.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a liquid crystal / in-situ open-ring polymer electrolyte, a lithium-ion battery, and a method for preparing the same. Background Technology

[0002] Rechargeable lithium-ion batteries, with their advantages of high energy density, long cycle life, no memory effect, and low self-discharge, have been widely researched and commercialized, becoming one of the most important battery devices. However, currently used carbonate-based electrolytes typically contain large amounts of linear carbonates, posing a significant safety hazard to lithium-ion batteries due to their high flammability and leakage risk. Compared to liquid electrolytes, inherently non-flammable solid-state electrolytes can fundamentally solve battery safety issues, and their introduction can further improve battery energy density. However, the high interfacial impedance caused by the solid-solid interface formed between the electrolyte and the electrodes, along with the electrolyte's inherent low conductivity, severely limits the practical application of solid-state electrolytes in lithium-ion batteries.

[0003] In-situ polymerization technology involves injecting a liquid precursor into the battery, allowing it to fully wet the electrodes, and then solidifying it in situ. This approach addresses safety concerns while ensuring good interfacial contact. The monomers used in in-situ polymerization primarily include cyclic ethers, acrylates, and monomers containing unsaturated double bonds. Among these, cyclic ether monomers have attracted attention due to their good interfacial compatibility with lithium metal and the excellent electrochemical performance of solid electrolytes formed through in-situ ring-opening polymerization. However, in-situ thermal polymerization requires the addition of an initiator, and initiator residue often promotes violent side reactions on the electrode surface. Insufficient initiator content leads to incomplete monomer polymerization. Therefore, the selection and optimization of initiators are crucial for in-situ polymerization of electrolytes. Furthermore, improving the ionic conductivity of the electrolyte while ensuring its oxidative stability is an urgent requirement for promoting the application of cyclic ether in-situ polymerized solid electrolytes in high-energy lithium-ion batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid crystal / in-situ ring-opening polymer electrolyte, a lithium-ion battery, and a method for preparing the same. Using an in-situ ring-opening polymer as the main matrix and liquid crystal as the organic solid-state filler, the room-temperature conductivity of the polymer electrolyte reaches 1*10⁻⁶. -4 S cm -1 Ultimately, these technologies are applied in lithium-ion batteries.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] The first objective of this invention is to provide a liquid crystal / in-situ ring-opening polymer electrolyte, composed of liquid crystal monomers, cyclic ethers, and lithium salts.

[0007] The liquid crystal monomer is selected from one of the following structural formulas (I), (II), (III) and (IV).

[0008]

[0009] Wherein, A is selected from -C≡N, C1-C10 alkyl chain or -O-(CH2)m-CH3, where m is an integer from 0 to 9; B is selected from -C≡N, C1-C10 alkyl chain or -O-(CH2)n-CH3, where n is an integer from 0 to 9; Fx indicates that x hydrogen atoms on the benzene ring are replaced by fluorine atoms, and x is an integer from 0 to 4.

[0010] In one embodiment of the present invention, the C1-C10 alkyl chain refers to an alkyl chain containing 1 to 10 carbon atoms.

[0011] In one embodiment of the present invention, A and B are selected from -C≡N and -(CH2). m -CH3, -O-(CH2) n -CH3, any one of them, where m is an integer from 0 to 9 and n is an integer from 0 to 9.

[0012] Preferably, the liquid crystal monomer is selected from one of the following structures;

[0013]

[0014] Preferably, the cyclic ether comprises one or more of ethylene oxide, tetrahydrofuran, 1,3-dioxolane, dioxane, or trioxane.

[0015] Preferably, the lithium salt comprises one or more of lithium difluorophosphate, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroborate, lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonylimide), lithium bis(difluorosulfonylimide), lithium dioxalateborate, lithium difluorooxalateborate, or lithium malonate oxalateborate.

[0016] When liquid crystal materials transition from a crystalline to a liquid state, they first lose their positional order and acquire liquid fluidity, while retaining some of the anisotropic orientation of the crystalline material, forming an intermediate state that combines properties of both crystalline and liquid components. Liquid crystals with high anchoring strength facilitate the deposition of metallic lithium and inhibit the growth of lithium dendrites. Currently reported liquid crystal electrolytes still have insufficient ionic conductivity, and at room temperature, they struggle to balance mechanical strength and good electrochemical performance. Therefore, this invention provides a simple and efficient method for preparing a liquid crystal polymer electrolyte that combines high ionic conductivity and mechanical properties by mixing liquid crystal materials with cyclic ether monomers and then polymerizing them in situ.

[0017] A second objective of this invention is to provide a method for preparing a liquid crystal / in-situ ring-opening polymer electrolyte, comprising the following steps:

[0018] (1) Mix the liquid crystal monomer, cyclic ether and lithium salt to form a mixture;

[0019] (2) The mixture prepared in step (1) is subjected to a polymerization reaction to obtain a liquid crystal / in-situ ring-opening polymer electrolyte.

[0020] Preferably, in step (1), the ratio of liquid crystal monomer, cyclic ether and lithium salt is 0.1g~0.3g:0.7~0.9g:1mol.

[0021] Preferably, in step (1), the temperature during the mixing process is 20–80°C.

[0022] Preferably, in step (2), the temperature during the polymerization reaction is 30–90°C and the time is 12–48 h.

[0023] In one embodiment of the present invention, in step (2), the polymerization is the cationic polymerization of cyclic ethers through ring-opening.

[0024] A third objective of this invention is to provide a lithium-ion battery comprising the aforementioned liquid crystal / in-situ open-ring polymer electrolyte, and further comprising a positive electrode and a negative electrode.

[0025] Preferably, the active material in the positive electrode is selected from one or more of lithium, iron, cobalt, nickel, manganese or phosphorus.

[0026] More preferably, the positive electrode active material is doped or coated with one or more elements selected from aluminum, magnesium, zirconium, titanium, lanthanum, nickel, manganese or yttrium.

[0027] More preferably, the positive electrode active material is selected from one of lithium iron phosphate, lithium cobalt oxide, lithium nickel manganese oxide, or nickel-cobalt-manganese ternary positive electrode materials.

[0028] Preferably, the active material in the negative electrode is selected from one or more of lithium metal, carbon-based materials, silicon-based materials, and transition metal oxides.

[0029] The fourth objective of this invention is to provide a method for preparing a lithium-ion battery, comprising the following steps: injecting a liquid crystal / in-situ open-ring polymer electrolyte between a positive electrode and a negative electrode and then curing it in situ to obtain a lithium-ion battery with a polymer electrolyte.

[0030] The lithium-ion battery is a solid-state lithium-ion battery.

[0031] In one embodiment of the present invention, the method for preparing the lithium-ion battery is as follows:

[0032] (1) Place the separator on the dried positive electrode, and dissolve the liquid crystal monomer, cyclic ether and lithium salt at a certain temperature to form a uniform solution. Then, evenly drop the uniformly mixed solution onto the separator so that the solution fully wets the separator and penetrates into the surface of the positive electrode material. Then, encapsulate it with the negative electrode.

[0033] (2) After the battery has been left to stand for a period of time, charge and discharge it several times under low current density conditions to generate a stable SEI film on the electrode surface.

[0034] (3) The battery is placed at a certain temperature to undergo a polymerization reaction to obtain a lithium-ion battery containing the liquid crystal / in-situ open-ring polymer electrolyte.

[0035] Preferably, in step (1), the diaphragm is selected from one of polyurethane (PI) diaphragm, glass fiber (GF) diaphragm, polyethylene (PE) diaphragm, polypropylene (PP) diaphragm, polyethylene-polypropylene composite diaphragm, or polyethylene-polypropylene composite diaphragm with aluminum oxide coated on the surface; the dissolution temperature is 20℃~80℃;

[0036] Preferably, in step (2), the settling time is 1 to 72 hours;

[0037] Preferably, in step (2), the current density ranges from 10 to 5000 mA / cm². 2 ;

[0038] Preferably, in step (2), the number of charge-discharge cycles is 1 to 20, including the case where the last cycle only charges and does not discharge;

[0039] Preferably, in step (3), the polymerization temperature is 30℃~90℃.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] 1. This invention provides a method for preparing liquid crystal / in-situ ring-opening polymer electrolytes. Compared with photopolymerization, in-situ thermal polymerization can achieve ring-opening polymerization of monomers after battery assembly, which can effectively improve the compatibility of the electrolyte-electrode interface, and has the advantages of being environmentally friendly, simple and convenient to operate, and automated. This method is simple and efficient, and suitable for industrial applications.

[0042] 2. The present invention can effectively optimize the composition of the SEI film and CEI film on the electrode surface by using low current cycling before the electrolyte precursor solution is solidified, thereby enabling the assembled lithium-ion battery to have excellent cycle stability.

[0043] 3. The liquid crystal / in-situ open-ring polymer electrolyte prepared by the method provided in this invention constructs a liquid-like ion transport channel composed of liquid crystal, and its room temperature conductivity is at least one order of magnitude higher than that of the traditional PEO electrolyte.

[0044] 4. The in-situ polymerization technology used in this invention can fully impregnate the electrolyte precursor solution into the positive and negative electrode materials of the battery, causing the small molecule monomers therein to undergo a polymerization reaction to form a high molecular polymer skeleton, thereby fully protecting the structure of the positive and negative electrodes, inhibiting the volume expansion of the electrodes, protecting the integrity of the electrode structure, and preventing electrolyte leakage, thus improving the safety performance of the battery.

[0045] 5. The liquid crystal / in-situ ring-opening polymer electrolyte of this invention uses an in-situ ring-opening polymer as the main matrix and liquid crystal as the organic solid filler material, enabling the room temperature conductivity of the polymer electrolyte to reach 1*10. -4 S cm -1 Ultimately, these technologies are applied in lithium-ion batteries. Attached Figure Description

[0046] Figure 1 The conductivity-impedance diagram of the liquid crystal / in-situ open-ring polymer electrolyte provided in Example 1 of the present invention after three cycles at 0.1C in an LFP|lithium metal battery at room temperature.

[0047] Figure 2 The first charge-discharge curve of the liquid crystal / in-situ open-ring polymer electrolyte provided in Embodiment 1 of the present invention.

[0048] Figure 3 The diagram shows the room temperature charge-discharge cycle diagrams of the liquid crystal / in-situ open-ring polymer electrolyte provided in Example 1 of the present invention and the liquid crystal-free in-situ open-ring polymer assembled lithium-ion batteries provided in Comparative Examples 1 and 2.

[0049] Figure 4 The LSV curve of the liquid crystal / in-situ open-ring polymer electrolyte provided in Embodiment 2 of the present invention is shown. Detailed Implementation

[0050] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0051] Unless otherwise specified, the reagents used in the following embodiments are commercially available reagents, and the detection methods and techniques used are conventional detection methods and techniques in the art.

[0052] Example 1

[0053] This embodiment provides a liquid crystal / in-situ open-ring polymer electrolyte and its preparation method.

[0054] The chemical structural formula of the liquid crystal used in this embodiment is shown below:

[0055]

[0056] In an argon-filled glove box, 0.9 g of 1,3-dioxolane (DOL) and 0.1 g of liquid crystal were weighed out by weight. LiTFSI (0.8 M) and LiDFOB (0.2 M) were also weighed out to prepare lithium salt solutions. After thorough mixing at room temperature, LiTFSI and LiDFOB were slowly added and stirred until completely dissolved, yielding a clear and transparent solution-electrolyte precursor. Sample vials containing the electrolyte precursor solution were placed at 55°C for 24 hours to allow for complete polymerization of the monomers in the electrolyte precursor, resulting in a solid electrolyte-liquid crystal / in-situ ring-opening polymer electrolyte. This solid electrolyte exhibited a clear and transparent solid state and completely lost its fluidity.

[0057] A liquid crystal / in-situ open-ring polymer electrolyte was injected and encapsulated between two stainless steel sheets, followed by in-situ curing to obtain a stainless steel symmetrical battery with the polymer electrolyte. The room-temperature ionic conductivity of the electrolyte in this embodiment was measured using AC impedance spectroscopy in a stainless steel / separator / stainless steel battery. The conductivity of the electrolyte in this embodiment reached a high level of 9.9 × 10⁻⁶. -4 Scm -1 The oxidation potential of the solid electrolyte in this embodiment was measured to be 4.48V, which can support commercial cathode materials such as lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium nickel cobalt manganese oxide (ternary materials).

[0058] A liquid crystal / in-situ open-ring polymer electrolyte is injected and encapsulated between a lithium metal sheet and a lithium iron phosphate positive electrode, followed by in-situ curing to obtain a stainless steel symmetrical battery with the polymer electrolyte. In this embodiment, the conductivity-impedance diagram of the lithium metal / lithium iron phosphate battery after three cycles at 0.1C at room temperature is shown below. Figure 1 As shown. The initial charge-discharge curves under the conditions of room temperature (25°C) and 0.1C rate are as follows. Figure 2 As shown. The initial discharge capacity of the liquid crystal / in-situ open-loop solid electrolyte in this embodiment is 167.5 mAh g. -1 Furthermore, the initial coulomb efficiency reached as high as 86.2%.

[0059] The cycle performance of the electrolyte was tested using a lithium metal / lithium iron phosphate battery system at a charge / discharge rate of 0.5C. Before the cycle test, two cycles at 0.1C were performed, followed by a 24-hour resting period at 55°C to allow for complete polymerization of the monomers in the electrolyte precursor. The test results at room temperature (25°C) are as follows... Figure 3 As shown. During 100 charge-discharge cycles, the liquid crystal / in-situ open-loop solid electrolyte of this embodiment exhibits excellent room temperature cycling performance, with no significant capacity decay during discharge, and an initial discharge specific capacity of 152.1 mAh g. -1 After 100 cycles, the discharge specific capacity is still as high as 129.7 mAh g. -1 The capacity retention rate is as high as 85.3%.

[0060] Example 2

[0061] This embodiment provides a liquid crystal / in-situ open-ring polymer electrolyte and its preparation method.

[0062] The chemical structural formula of the liquid crystal used in this embodiment is shown below:

[0063]

[0064] In an argon-filled glove box, 0.7 g of DOL and 0.3 g of liquid crystal were weighed out by weight, along with 0.8 M LiTFSI and 0.2 M LiDFOB to prepare lithium salt solutions. After thorough mixing at room temperature, LiTFSI and LiDFOB were slowly added and stirred until completely dissolved, yielding a clear and transparent solution-electrolyte precursor. Sample vials containing the electrolyte precursor solution were placed at 55°C for 24 hours to allow for complete polymerization of the monomers in the electrolyte precursor, resulting in a solid electrolyte-liquid crystal / in-situ ring-opening polymer electrolyte. This solid electrolyte exhibited a clear and transparent solid state and completely lost its fluidity.

[0065] The room-temperature ionic conductivity of the electrolyte in this embodiment, measured using AC impedance spectroscopy in a stainless steel | separator | stainless steel battery, reached as high as 2.4 × 10⁻⁶. -3 S cm -1 The oxidative stability results of the solid electrolyte in this embodiment are as follows: Figure 4 As shown, when the voltage is below 4.52V, the current density is low and the electrolyte is relatively stable. When the voltage exceeds 4.52V, the current density increases rapidly, and the electrolyte begins to decompose. Therefore, the oxidation potential of this solid electrolyte is 4.52V, which can support commercial cathode materials such as lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium nickel cobalt manganese oxide (ternary materials).

[0066] In a lithium metal / lithium iron phosphate battery, at room temperature (25°C) and a rate of 0.1C, the initial discharge capacity of the liquid crystal / in-situ open-loop solid electrolyte in this embodiment is 165.6 mAh g. -1 Furthermore, the initial coulomb efficiency reached as high as 88.4%.

[0067] The cycle performance of the electrolyte was tested using a lithium metal / lithium iron phosphate battery system at a charge / discharge rate of 0.5C. The test results at 25℃ are as follows: Figure 4 As shown. During 100 charge-discharge cycles, the liquid crystal / in-situ open-loop solid electrolyte of this embodiment exhibits excellent room temperature cycling performance, with no significant capacity decay during discharge, and an initial discharge specific capacity of 160.5 mAh g. -1 After 100 cycles, the discharge specific capacity is still as high as 124.0 mAh g. -1 The capacity retention rate is as high as 81.7%.

[0068] Example 3

[0069] This embodiment provides a liquid crystal / in-situ open-ring polymer electrolyte and its preparation method.

[0070] The chemical structural formula of the liquid crystal used in this embodiment is shown below:

[0071]

[0072] In an argon-filled glove box, 0.9 g of DOL and 0.1 g of liquid crystal were weighed out by weight, along with 0.6 M LiTFSI and 0.4 M LiDFOB to prepare lithium salt solutions. After thorough mixing at room temperature, LiTFSI and LiDFOB were slowly added and stirred until completely dissolved, yielding a clear and transparent solution-electrolyte precursor. Sample vials containing the electrolyte precursor solution were placed at 55°C for 24 hours to allow for complete polymerization of the monomers in the electrolyte precursor, resulting in a solid electrolyte-liquid crystal / in-situ ring-opening polymer electrolyte. This solid electrolyte exhibited a clear and transparent solid state and completely lost its fluidity.

[0073] The room-temperature ionic conductivity of the electrolyte in this embodiment, measured using AC impedance spectroscopy in a stainless steel / membrane / stainless steel battery, reached as high as 3.4 × 10⁻⁶. -3 S cm -1 The solid electrolyte in this embodiment has an oxidation potential of 4.45V, which can support commercial cathode materials such as lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium nickel cobalt manganese oxide (ternary materials).

[0074] In a lithium metal / lithium iron phosphate battery, under room temperature (25°C) and 0.1C rate conditions, the initial discharge capacity of the liquid crystal / in-situ open-loop solid electrolyte in this embodiment is 165.7 mAh g. -1 Furthermore, the initial coulomb efficiency reached as high as 80.8%.

[0075] The cycling performance of the electrolyte was tested using a lithium metal / lithium iron phosphate battery system at a charge / discharge rate of 0.5C. Before the cycling test, two cycles at 0.1C were performed, followed by a 24-hour resting period at 55°C to allow for complete polymerization of the monomers in the electrolyte precursor. During 100 charge / discharge cycles, the liquid crystal / in-situ open-loop solid-state electrolyte of this embodiment exhibited excellent room-temperature cycling performance, with no significant capacity decay during discharge, and an initial discharge specific capacity of 161.5 mAh g⁻¹. -1 After 100 cycles, the discharge specific capacity is still as high as 112.8 mAh g. -1 The capacity retention rate is as high as 81.9%.

[0076] Example 4

[0077] This embodiment provides a liquid crystal / in-situ open-ring polymer electrolyte and its preparation method.

[0078] The chemical structural formula of the liquid crystal used in this embodiment is shown below:

[0079]

[0080] In an argon-filled glove box, 0.9 g of DOL and 0.1 g of liquid crystal were weighed out by weight, along with 0.8 M LiTFSI and 0.2 M LiDFOB to prepare lithium salt solutions. After thorough mixing at room temperature, LiTFSI and LiDFOB were slowly added and stirred until completely dissolved, yielding a clear and transparent solution-electrolyte precursor. Sample vials containing the electrolyte precursor solution were placed at 55°C for 24 hours to allow for complete polymerization of the monomers in the electrolyte precursor, resulting in a solid electrolyte-liquid crystal / in-situ ring-opening polymer electrolyte. This solid electrolyte exhibited a clear and transparent solid state and completely lost its fluidity.

[0081] The room-temperature ionic conductivity of the electrolyte in this embodiment, measured using AC impedance spectroscopy in a stainless steel / membrane / stainless steel battery, reached as high as 1.7 × 10⁻⁶. -3 S cm -1 The solid electrolyte in this embodiment has an oxidation potential of 4.61V, which can support commercial cathode materials such as lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and lithium nickel cobalt manganese oxide (ternary materials).

[0082] In a lithium metal / lithium iron phosphate battery, at room temperature (25°C) and a rate of 0.1C, the initial discharge capacity of the liquid crystal / in-situ open-loop solid electrolyte in this embodiment is 163.2 mAh g. -1 Furthermore, the initial coulomb efficiency reached as high as 84.5%.

[0083] The cycle performance of the electrolyte was tested using a lithium metal / lithium iron phosphate battery system at a charge / discharge rate of 0.5C. Before the cycle test, two cycles at 0.1C were performed, followed by a 24-hour resting period at 55°C to allow for complete polymerization of the monomers in the electrolyte precursor. During 100 charge / discharge cycles, the liquid crystal / in-situ open-loop solid-state electrolyte of this embodiment exhibited excellent room-temperature cycle performance, with no significant capacity decay during discharge, and an initial discharge specific capacity of 153.5 mAh g⁻¹. -1 After 100 cycles, the discharge specific capacity is still as high as 129.4 mAh g. -1 The capacity retention rate was 84.3%.

[0084] Comparative Example 1

[0085] In an argon-filled glove box, 1 g of DOL was weighed, along with 0.8 M LiTFSI and 0.2 M LiDFOB. After thorough mixing at room temperature, LiTFSI and LiDFOB were slowly added and stirred until completely dissolved, yielding a clear and transparent solution-electrolyte precursor. The sample vial containing the electrolyte precursor solution was placed at 55°C for 24 hours to allow for complete polymerization of the monomers in the electrolyte precursor, resulting in a solid electrolyte. This solid electrolyte exhibited a clear and transparent solid state and completely lost its fluidity.

[0086] The room-temperature ionic conductivity of the electrolyte in this comparative example, measured using AC impedance spectroscopy in a stainless steel / diaphragm / stainless steel battery, was 3.4 × 10⁻⁶. -5 S cm -1 .

[0087] In this comparative example, the initial discharge capacity of a lithium metal / lithium iron phosphate battery at room temperature (25°C) and a 1C rate is 156.8 mAh g. -1 Furthermore, the initial Coulomb efficiency was 98.1%.

[0088] The cycle performance of the electrolyte was tested using a lithium metal / lithium iron phosphate battery system at a charge / discharge rate of 0.5C. After battery assembly, the cells were allowed to stand for 10 hours, followed by polymerization at 55°C for 24 hours. Cyclic test results at room temperature (25°C) are as follows... Figure 3 As shown, during 100 charge-discharge cycles, the liquid crystal / in-situ open-loop solid electrolyte of this comparative example exhibited excellent room-temperature cycling performance, but its discharge capacity showed significant decay, with the initial discharge specific capacity being only 7.3 mAh g⁻¹. -1 After 100 cycles, the discharge specific capacity is almost zero.

[0089] Comparative Example 2

[0090] The solid electrolyte of Comparative Example 2 was prepared by the same method as that of Comparative Example 1.

[0091] The cycle performance of the electrolyte was tested using a lithium metal / lithium iron phosphate battery system at a charge / discharge rate of 0.5C. Before the cycle test, the battery was first cycled twice at 0.1C, followed by a 24-hour resting period at 55°C to allow for complete polymerization of the monomers in the electrolyte precursor. The battery cycle performance at 25°C was as follows: Figure 3 As shown. During 100 charge-discharge cycles, the liquid crystal / in-situ open-loop solid electrolyte of this comparative example exhibits excellent room temperature cycling performance, but the discharge capacity shows a significant decay, with an initial discharge specific capacity of 147.1 mAh g⁻¹. -1 After 100 cycles, the discharge specific capacity is 29.9 mAh g. -1 The capacity retention rate was 20.3%; the conductivity and performance test results are shown in Table 1.

[0092] Table 1 Conductivity and Performance Test Table

[0093]

[0094]

[0095] As shown in the table above, this invention enables the polymer electrolyte to achieve a room temperature conductivity of 1*10⁻⁶. -4 S cm -1 The above levels have remained at approximately 10. -3 Magnitude.

[0096] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A liquid crystal / in-situ ring-opening polymer electrolyte, characterized in that, Composed of liquid crystal monomers, cyclic ethers, and lithium salts, The liquid crystal monomer is selected from one of the following structural formulas (I), (II), (III) and (IV). Wherein, A is selected from -C≡N, C1-C10 alkyl chain or -O-(CH2)m-CH3, where m is an integer from 0 to 9; B is selected from -C≡N, C1-C10 alkyl chain or -O-(CH2)n-CH3, where n is an integer from 0 to 9; Fx indicates that x hydrogen atoms on the benzene ring are replaced by fluorine atoms, and x is an integer from 0 to 4.

2. The liquid crystal / in-situ ring-opening polymer electrolyte according to claim 1, characterized in that, The liquid crystal monomer is selected from one of the following structures; 3. The liquid crystal / in-situ ring-opening polymer electrolyte according to claim 1, characterized in that, The cyclic ether includes one or more of ethylene oxide, tetrahydrofuran, 1,3-dioxolane, dioxane, or trioxane.

4. The liquid crystal / in-situ ring-opening polymer electrolyte according to claim 1, characterized in that, The lithium salt includes one or more of lithium difluorophosphate, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroborate, lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonylimide), lithium bis(difluorosulfonylimide), lithium dioxalate borate, lithium difluorooxalate borate, or lithium malonate oxalate borate.

5. A method for preparing a liquid crystal / in-situ ring-opening polymer electrolyte as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Mix the liquid crystal monomer, cyclic ether and lithium salt to form a mixture; (2) The mixture prepared in step (1) is subjected to a polymerization reaction to obtain a liquid crystal / in-situ ring-opening polymer electrolyte.

6. The method for preparing liquid crystal / in-situ ring-opening polymer electrolyte according to claim 5, characterized in that, In step (1), the ratio of liquid crystal monomer, cyclic ether and lithium salt is 0.1g~0.3g:0.7~0.9g:1mol.

7. The method for preparing liquid crystal / in-situ ring-opening polymer electrolyte according to claim 5, characterized in that, In step (1), the temperature is 20-80℃ during the mixing process.

8. The method for preparing liquid crystal / in-situ ring-opening polymer electrolyte according to claim 5, characterized in that, In step (2), the polymerization reaction is carried out at a temperature of 30–90°C for 12–48 hours.

9. A lithium-ion battery, characterized in that, The lithium-ion battery comprises the liquid crystal / in-situ open-ring polymer electrolyte as described in any one of claims 1 to 4; The lithium-ion battery also includes a positive electrode and a negative electrode; The active material in the positive electrode is selected from one or more of lithium, iron, cobalt, nickel, manganese or phosphorus; the active material in the negative electrode is selected from one or more of metallic lithium, carbon-based materials, silicon-based materials or transition metal oxides.

10. A method for preparing a lithium-ion battery as described in claim 9, characterized in that, Includes the following steps: A lithium-ion battery with a polymer electrolyte is obtained by injecting liquid crystal / in-situ open-ring polymer electrolyte between the positive and negative electrode plates and then curing it in situ.

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